The present invention relates to a mine roof support, particularly to a shield mine roof support.
Mine roof supports of the above-mentioned general type are known in the art. A known mine roof support is introduced into a mine gallery and works in the mine face by a mining device which is displaceable in direction of elongation of the mine gallery. The cutting width of the mining device is considerably greater than the cutting depth of a planning tool or a cutting machine. The cutting width may be equal for example to between three meters and 3.5 meters. The cutting tool is composed of an elongated one-part or multi-part roller-shaped material removing drum with an approximately horizontal axis of rotation. The material removing drum is arranged at an end face of the machine body of the mining device and is raisable and lowerable in the vertical plane. The removed mineral is conveyed via an intermediate conveyor provided on the mining device, onto a gallery conveyor which is displaceable along the mine face and delivers the mineral to a conveyor provided in the subsidiary gallery.
The mining device has the considerable cutting width and thereby great freely lying roof areas take place and special mining processes must be utilized. In this condition, it is necessary to support by an additional thrust prop the mine face end of the roof-supporting element of the mine roof support extending from the travel field to the mining field, before and after the passage of the mining device. In connection with this, individual props are known which can be displaced by hand and installed, after the passage of the mining device, under the free end of the displaced rood-supporting element, particularly under the projecting longitudinal portion of the roof supporting element.
It is also known to arrange the thrust prop directly in the roof supporting element and to pivot the same in the plane of the roof-supporting element. This pivoting is performed, as a rule, in longitudinal direction of the roof supporting element, inasmuch as here the space is available for accommodating the thrust prop. Thrust props are also known in the art which can be pivoted in a plane which is parallel to the mine face. They are, however, utilized only in the case when the respective deposits have a relatively small thickness. The thrust prop which is centrally articulated on the roof supporting element can, because it is short, always be pivoted in the plane of the roof supporting element, so that when the thrust prop is extended it assumes a supporting position in which it lies substantially in the vertical central longitudinal plane of the mine roof support. These possibilities are, however, limited inasmuch as in condition of increasing deposit thicknesses the lengths of the props also increase and the telescopable props can no longer guarantee the central momentum-free support of the mine face end of the roof supporting element and to provide for pivoting of the prop in the plane of the roof supporting element. The minimum length of such a prop considerably exceeds the half width of the roof supporting element in the region of the mine face. An off-central connection results in high torsion moment in the roof-supporting element.